Fuel Cell Gas Diffusion Layer Integrated Gasket

ABSTRACT

A gas diffusion layer-integrated gasket  1  includes a first gasket  12  which is integrally molded to a periphery of a first gas diffusion layer  11  and a second gasket  14  which is integrally molded to a periphery of a second gas diffusion layer  13,  and a hinge part  15  which connects the first gasket  12  and second gasket  14  to each other. The first and second gas diffusion layers sandwich a membrane-electrode assembly  2  in which catalytic electrode layers are provided on both surfaces of an electrolytic membrane from both sides, wherein a seal protrusion  12   c  is formed on a surface which is in tight contact with the membrane-electrode assembly  2.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit and priority of Japanese PatentApplication No. 2009-210482, filed Sep. 11, 2009 and Japanese PatentApplication No. 2009-168653, filed Jul. 17, 2009. The entire disclosuresof each of the above applications are incorporated herein by reference.

FIELD

The present disclosure relates to a gasket which is integrally providedin a gas diffusion layer and used for sealing reaction gas in a fuelcell.

BACKGROUND

This section provides background information related to the presentdisclosure which is not necessarily prior art.

In a fuel cell, as shown in FIG. 15, a fuel-cell cell 100, which is thesmallest unit that generates power, is constructed by sandwiching amembrane-electrode assembly (MEA) 101, consisting of an electrolyticmembrane and catalytic electrode layers (not shown in diagram), on bothsides of it with two separators 104 and 105 and two gas diffusion layers(GDLs) 102 and 103.

On both sides of the membrane electrode assembly 101 in the direction ofthickness, a first gasket 106 and a second gasket 107 are each made froma rubber-like elastic material (rubber material or synthetic resinmaterial having rubber-like elasticity) are arranged. Also, between onecatalytic electrode layer on the membrane electrode assembly 101 and oneseparator 104 which opposes it, a fuel gas channel 100 a, for example,is formed by the first gasket 106, and between the other catalyticelectrode layer on the membrane electrode assembly 101 and the otherseparator 105 which opposes it, an oxidant gas channel 100 b, forexample, is formed by the second gasket 107.

That is, in this type of fuel cell, in each fuel-cell cell 100, fuel gas(hydrogen) which passes through the fuel gas channel 100 a is suppliedto one catalytic electrode layer (anode) side of the membrane-electrodeassembly 101 via a first gas diffusion layer 102, and oxidant gas (air)which passes through the oxidant gas channel 100 b is supplied to theother catalytic electrode layer (cathode) side of the membrane-electrodeassembly 101 via a second gas diffusion layer 103, and power isgenerated by a reaction which is the reverse of electrolysis ofwater—that is, a reaction in which water is produced from hydrogen andoxygen. Although the electromotive force produced by each fuel-cell cell100 is small, the required electromotive force can be obtained bystacking a plurality of fuel-cell cells 100 and electrically connectingthem in series (for example, refer to patent reference 1).

SUMMARY

This section provides a general summary of the disclosure, and is not acomprehensive disclosure of its full scope or all of its features.

However, in this type of fuel cell, the fact that the first gasket 106and the second gasket 107 are integrally molded in themembrane-electrode assembly 101 leads to risk of the membrane-electrodeassembly 101 being easily damaged by heat during molding, and the factthat the first gasket 106 and the second gasket 107 are integrallymolded in the first gas diffusion layer 102 and the second gas diffusionlayer 103 leads to the problem that there are many molding steps andparts, and the precision of assembly of the fuel-cell cells 100 tends tobe low.

Taking the above points into consideration, the technical problems ofthe present disclosure are to improve the assembly precision of fuelcells and to obtain good sealing ability.

As means for effectively resolving the above technical problems, a gasdiffusion layer-integrated gasket for a fuel cell comprises a firstgasket which is integrally molded in a first gas diffusion layer and arim part thereof, a second gasket which is integrally molded in a secondgas diffusion layer and a rim part thereof, and a hinge part whichconnects the aforementioned first gasket and second gasket to eachother, which sandwiches a membrane-electrode assembly in which catalyticelectrode layers are provided on both surfaces of an electrolyticmembrane from both sides in the direction of thickness, wherein a sealprotrusion is formed on a surface which is in tight contact with theaforementioned membrane-electrode assembly on the aforementioned firstgasket or second gasket.

Also, the gas diffusion layer-integrated gasket for a fuel cell includesa fitting protrusion on the first gasket and a fitting hole orindentation on the second gasket which can fit with the aforementionedfitting protrusion and is formed at a position symmetrical to theaforementioned fitting protrusion, with the hinge part as the axis ofsymmetry.

According to the gas diffusion layer-integrated gasket for a fuel cell,because the first gasket and second gasket are connected to each othervia a hinge part and are integrally molded in the rim parts of the firstgas diffusion layer and second gas diffusion layer, respectively, thenumber of parts is reduced. And, because the membrane-electrode assemblyis sandwiched between the first gas diffusion layer and first gasket andthe second gas diffusion layer and second gasket is tightly affixed bythe compression force of the seal protrusion formed on the first gasketand second gasket, assembly precision is improved, and furthermore,sealing ability with the membrane-electrode assembly is improved by thecompression force of the aforementioned seal protrusion.

According to the gas diffusion layer-integrated gasket for a fuel cell,when the membrane-electrode assembly is sandwiched by the first gasketand second gasket from both sides in the direction of thickness, afitting protrusion and a fitting hole or fitting indentation, which areformed in positions symmetrical to each other with the hinge part as theaxis of symmetry on the first gasket or second gasket, fit together witheach other, and as a result, the first gasket and second gasket aremutually positioned with high precision, and therefore, decreasedsealing ability due to stacking offset of the first and second gasketsis prevented.

Further areas of applicability will become apparent from the descriptionprovided herein. The description and specific examples in this summaryare intended for purposes of illustration only and are not intended tolimit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustrative purposes only ofselected embodiments and not all possible implementations, and are notintended to limit the scope of the present disclosure.

FIG. 1 is a partial cross-sectional view which illustrates a fuel-cellcell comprising a gas diffusion layer-integrated gasket for a fuel cellpertaining to a first embodiment of the present disclosure;

FIG. 2 is a plan view which illustrates a gas diffusion layer-integratedgasket for a fuel cell pertaining to a first embodiment of the presentdisclosure;

FIG. 3 is a cross-sectional view along line III-III of FIG. 2;

FIGS. 4A and 4B are explanatory diagrams which illustrate the process ofsandwiching the membrane-electrode assembly by a gas diffusionlayer-integrated gasket for a fuel cell pertaining to a first embodimentof the present disclosure;

FIG. 5 is a partial cross-sectional view which illustrates the statewhere the membrane-electrode assembly has been sandwiched by a gasdiffusion layer-integrated gasket for a fuel cell pertaining to a firstembodiment of the present disclosure;

FIG. 6 is an explanatory diagram which schematically illustrates themechanism of power generation in a fuel-cell cell;

FIG. 7 is a partial cross-sectional view which illustrates the state ofposition offset when the membrane-electrode assembly is sandwiched by agas diffusion layer-integrated gasket for a fuel cell pertaining to afirst embodiment of the present disclosure;

FIG. 8 is a plan view which illustrates a gas diffusion layer-integratedgasket for a fuel cell pertaining to a second embodiment of the presentdisclosure;

FIG. 9 is a perspective view which illustrates the process ofsandwiching the membrane-electrode assembly by a gas diffusionlayer-integrated gasket for a fuel cell pertaining to a secondembodiment of the present disclosure;

FIG. 10 is a perspective view which illustrates the state where themembrane-electrode assembly has been sandwiched by a gas diffusionlayer-integrated gasket for a fuel cell pertaining to a secondembodiment of the present disclosure;

FIG. 11 is a cross-sectional view which illustrates the state of fittingbetween a fitting protrusion and fitting hole;

FIG. 12 is a plan view which illustrates a gas diffusionlayer-integrated gasket for a fuel cell pertaining to a third embodimentof the present disclosure;

FIG. 13 is a cross-sectional view which illustrates the state of fittingbetween a fitting protrusion and a fitting indentation of a gasdiffusion layer-integrated gasket for a fuel cell pertaining to a fourthembodiment of the present disclosure;

FIG. 14 is a perspective view which illustrates a gas diffusionlayer-integrated gasket for a fuel cell pertaining to a fifth embodimentof the present disclosure;

FIG. 15 is a partial cross-sectional view which illustrates a fuel-cellcell comprising a gas diffusion layer-integrated gasket for a fuel cellaccording to prior art;

Corresponding reference numerals indicate corresponding parts throughoutthe several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference tothe accompanying drawings.

Preferred embodiments of the gas diffusion layer-integrated gasket for afuel cell pertaining to the present disclosure are described in detailbelow in reference to the drawings.

First, FIG. 1 shows a fuel-cell cell comprising a gas diffusionlayer-integrated gasket for a fuel cell pertaining to a first embodimentof the present disclosure. In the drawing, reference numeral 1 is a gasdiffusion layer-integrated gasket; reference numeral 2 is amembrane-electrode assembly consisting of an electrolytic membrane andcatalytic electrode layers provided on both sides of it, which issandwiched by the gas diffusion layer-integrated gasket 1; referencenumerals 3 and 4 are first and second separators arranged such that theysandwich the gas diffusion layer-integrated gasket 1 which sandwichesthe membrane-electrode assembly 2.

FIG. 2 is a plan view which illustrates a gas diffusion layer-integratedgasket for a fuel cell pertaining to the first embodiment of the presentdisclosure. FIG. 3 is a cross-sectional view along line III-III of FIG.2. As shown in FIG. 2 and FIG. 3, the gas diffusion layer-integratedgasket 1 comprises a first gasket 12 which is integrally molded in afirst gas diffusion layer 11 and a rim part thereof, a second gasket 14which is integrally molded in a second gas diffusion layer 13 and a rimpart thereof, and a hinge part 15 which connects the two gaskets 12 and14 to each other.

More specifically, the first gas diffusion layer 11 and second gasdiffusion layer 13 in the gas diffusion layer-integrated gasket 1 areformed into plates or sheets of the same size and shape as each otherfrom a metal porous body or a porous material such as carbon fiber, forexample.

The first gasket 12 and second gasket 14 in the gas diffusionlayer-integrated gasket 1 are made from a material selected fromrubber-like elastic materials (rubber material or synthetic resinmaterial having rubber-like elasticity), preferably ethylene propylenerubber (EPDM), silicone rubber (VMQ), fluorine rubber (FKM), perfluororubber (FFKM) and the like. They are formed symmetrically to each otherwith the hinge part 15 as the axis of symmetry, and they respectivelyhave base parts 12 a and 14 a, which are integrated by impregnation inthe rim part of the first gas diffusion layer 11 and second gasdiffusion layer 13, and main ribs 12 b and 14 b, which protrude from oneside to form cross-sectional ridges.

That is, the gas diffusion layer-integrated gasket 1 is integrallymolded by positioning the first gas diffusion layer 11 and second gasdiffusion layer 13 inside a specified mold (not shown in diagram), andthen, by tightening the mold, making the liquid molding material fillthe cavities formed between the aforementioned first gas diffusion layer11 and second diffusion layer 13 and the inner surface of theaforementioned mold. Therefore, concerns about the membrane-electrodeassembly 2 being damaged by heat, as in the case where the gaskets areintegrally molded with the membrane-electrode assembly 2, areeliminated.

Also, on the edges of the first gasket 12, as shown in FIG. 2, aplurality of pairs of manifold holes 121 and 122 are provided, whichconstitute the respective supply channels and drainage channels of thefuel gas, oxidant gas, coolant and so forth. Similarly, on the edge ofthe second gasket 14, a plurality of pairs of manifold holes 141 and142, which constitute the respective supply channels and drainagechannels of the fuel gas, oxidant gas, coolant and so forth, areprovided in positions having line symmetry with the manifold holes 121and 122 of the first gasket 12, with the hinge part 15 as the axis ofsymmetry. The main ribs 12 b and 14 b divide the fuel gas channels,oxidant gas channels and coolant channels including the manifold holes121, 122, 141 and 142 so that they are independent from each other, asshown by the double-dotted lines in FIG. 2.

On the surface opposite the main rib 12 b on the first gasket 12 of thegas diffusion layer-integrated gasket 1—in other words, on the surfacewhich is in tight contact with the membrane-electrode assembly 2 in thestacked state shown in FIG. 1—a seal protrusion 12 c having a smallcross-sectional area whose protrusion height is lower than the main rib12 b is formed continuously along a position which faces the back of themain rib 12 b, as shown in FIG. 3.

The hinge part 15 of the gas diffusion layer-integrated gasket 1 is madefrom a rubber-like elastic material which connects the first gasket 12and the second gasket 14. It is formed into a membrane shape which isthinner than the base parts 12 a and 14 a of the first gasket 12 andsecond gasket 14, such that it can easily bend. Also, the hinge part 15is made even more easily bendable by a specified number of slits 15 aformed in the bending part of the hinge part 15.

FIGS. 4A and 4B illustrate the process of sandwiching themembrane-electrode assembly by a gas diffusion layer-integrated gasketpertaining to the first embodiment of the present disclosure, and FIG. 5illustrates the state where the membrane-electrode assembly has beensandwiched. That is, in the gas diffusion layer-integrated gasket 1pertaining to the first embodiment of the present disclosure configuredas described above, as shown in FIG. 4A, the first gas diffusion layer11 and first gasket 12 and the second gas diffusion layer 13 and secondgasket 14 are folded together via the hinge part 15 such that the mainribs 12 b and 14 b oppose each other with respect to the direction ofthickness, while sandwiching the membrane-electrode assembly 2 from bothsides in the direction of thickness, as shown in FIG. 4B. In this state,the manifold holes 121 and 122 of the first gasket 12 and the manifoldholes 141 and 142 of the second gasket 14 shown in FIG. 2 overlap eachother.

In this case, the seal protrusion 12 c formed on the first gasket 12 isin tight contact with the membrane-electrode assembly 2 in thecompressed state, and, as shown in FIG. 5, a part 2 a of themembrane-electrode assembly 2 pushes on the second gasket 14 due to itscompression counterforce. Therefore, the membrane-electrode assembly 2is firmly sandwiched, and position offset can be prevented, and as aresult, the assembly precision of the fuel cell is improved.

Furthermore, the protrusion height and cross-sectional area of the sealprotrusion 12 c are appropriately set such that, in the stacked stateshown in FIG. 1, the membrane-electrode assembly 2 does not incur largebending deformation due to the compression counterforce of the sealprotrusion 12 c, and the first and second gaskets 12 and 14 and thefirst and second gas diffusion layers 11 and 13 do not partially rise upfrom the membrane-electrode assembly 2.

In the gas diffusion layer-integrated gasket 1, because the first gasket12 and second gasket 14 are connected to each other via a hinge part 15and they are integrally molded on the respective rim parts of the firstgas diffusion layer 11 and second gas diffusion layer 13, the number ofparts and the number of assembly steps can be greatly reduced.

In this way, using the gas diffusion layer-integrated gasket 1 whichsandwiches the membrane-electrode assembly 2, a fuel-cell cell 10, whichis the smallest unit that generates power, is constructed by sandwichinga membrane-electrode assembly 2 with first and second separators 3 and4.

The first separator 3 is made from an electrically conductive materialsuch as carbon or metal sheet. A groove 31 is formed on the surfaceopposite the first gas diffusion layer 11 in the gas diffusionlayer-integrated gasket 1, and by means of this groove 31, a firstreaction gas channel (for example, a fuel gas channel) F1 is formedbetween the first separator 3 and the first gas diffusion layer 11. Thefirst reaction gas channel F1 is connected to any of the plurality ofmanifold holes 121 and any of the plurality of manifold holes 122 shownin FIG. 2.

The second separator 4 is similar to the first separator 3. A groove 41is formed on the surface opposite the second gas diffusion layer 13 inthe gas diffusion layer-integrated gasket 1, and by means of this groove41, a second reaction gas channel (for example, an oxidant gas channel)F2 is formed between the second separator 4 and the second gas diffusionlayer 13. The second gas channel F2 is connected to manifold holes 141and 142, among the plurality of pairs of manifold holes 141 and 142shown in FIG. 2, which overlap manifold holes 121 and 122 at a positiondifferent from the first reaction gas channel F1.

In the stacked state shown in FIG. 1, due to the fact that the main rib12 b of the first gasket 12 in the gas diffusion layer-integrated gasket1 is in tight contact with the rim part of the first separator 3 in thestate where it is compressed with a specified squeeze, the region wherethe first reaction gas channel F1 is formed is separated so that it isindependent. Similarly, due to the fact that the main rib 14 b of thesecond gasket 14 in the gas diffusion layer-integrated gasket 1 is intight contact with the rim part of the second separator 4 in the statewhere it is compressed with a specified squeeze, the region where thesecond reaction gas channel F2 is formed is separated so that it isindependent.

In the fuel-cell cell 10 configured as described above, as shown in FIG.6, fuel gas containing hydrogen H₂, for example, is supplied to onecatalytic electrode layer (anode) 22 in the membrane-electrode assembly2 via the first reaction gas channel F1 and first gas diffusion layer11, and oxidant gas containing O₂ (air), for example, is supplied to theother catalytic electrode layer (cathode) 23 in the membrane-electrodeassembly 2 via the second reaction gas channel F2 and second gasdiffusion layer 13, and power is generated by an electrochemicalreaction which is the reverse of electrolysis of water—that is, areaction in which water H₂O is produced from hydrogen H₂ and oxygen O₂.

More specifically, the hydrogen H₂ in the fuel gas supplied from thefirst reaction gas channel F1 to the anode 22 in the membrane-electrodeassembly 2 via the first gas diffusion layer 11 is decomposed intoelectrons e⁻ and hydrogen ions H⁺ by the catalytic action of the anode22.

Then, the electrons e− produced in this way flow as current through anexternal load R toward the cathode 23 in the membrane-electrode assembly2. Also, since hydrogen ions H⁺ produced by dissociation of electrons e⁻from hydrogen H₂ are attracted to the electrons e- of the cathode 23,they migrate to the cathode 23 via the electrolytic membrane 21 in themembrane-electrode assembly 2.

On the other hand, the oxygen O₂ in the oxidant gas supplied from thesecond reaction gas channel F2 to the cathode 23 in themembrane-electrode assembly 2 via the second gas diffusion layer 13accepts electrons e⁻ by the catalytic action of the cathode 23. Then,oxygen ions O⁻ migrate from the anode 22 via the electrolytic membrane21 and bond with the arriving hydrogen ions H⁺, thereby producing waterH₂O.

Furthermore, although the electromotive force by a single fuel-cell cell10 is small, a fuel cell is normally constructed by electricallyconnecting many fuel-cell cells 10 in series by stacking, such that therequired electromotive force is obtained.

In this case, fuel gas which flows through the first reaction gaschannel F1 is sealed by the main rib 12 b of the first gasket 12 whichwas put in tight contact with the rim part of the first separator 3 witha specified squeeze, and the oxidant gas or produced water which flowsthrough the second reaction gas channel F2 is sealed by the main rib 14b of the second gasket 14 which was put in tight contact with the rimpart of the second separator 4 with a specified squeeze.

Also, the seal protrusion 12 c formed on the first gasket 12 is put intight contact with the membrane-electrode assembly 2 in the compressedstate, and, as shown in FIG. 5, a part 2 a of the membrane-electrodeassembly 2 pushes on the second gasket 14 due to its compressioncounterforce. Therefore, the contact surface pressure of the first andsecond gaskets 12 and 14 against the membrane-electrode assembly 2 islocally increased. Moreover, the compression counterforce of the firstand second gaskets 12 and 14 also effectively contributes to an increasein the contact surface pressure of the first and second gaskets 12 and14 against the membrane-electrode assembly 2 by the seal protrusion 12c. For this reason, fuel gas to be supplied from the first gas diffusionlayer 11 to one catalytic electrode layer 22 in the membrane-electrodeassembly 2 does not leak from the contact part between the first gasket12 and the membrane-electrode assembly 2, and oxidant gas to be suppliedfrom the second gas diffusion layer 14 to the other catalytic electrodelayer 23 in the membrane-electrode assembly 2 does not leak from thecontact part between the second gasket 14 and the membrane-electrodeassembly 2.

Furthermore, in the first embodiment described above, the sealprotrusion 12 c is formed on the first gasket 12, but the presentdisclosure is not limited to this configuration, and the seal protrusion12 c may be formed on the side opposite the main rib 14 b on the secondgasket 14 or on the surface which is in tight contact with themembrane-electrode assembly 2.

Also, in the first embodiment described above, fuel gas is supplied fromthe first reaction gas channel F1 and oxidant gas is supplied from thesecond reaction gas channel F2, but these can be reversed.

Furthermore, in the state where the membrane-electrode assembly 2 issandwiched by the gas diffusion layer-integrated gasket 1, if the firstgasket 12 and the second gasket 14 are positionally offset from eachother as shown in FIG. 7, the main ribs 12 b and 14 b also end up beingoffset from each other. Therefore, in the stacked state shown in FIG. 1,there is the concern that excellent sealing ability will not beobtained, because contact surface pressure against the first and secondseparators 3 and 4 due to the compression counterforce of the main ribs12 b and 14 b is diminished, and moreover, because the compressioncounterforce of the main ribs 12 b and 14 b do not effectively act toincrease the contact surface pressure of the first and second gaskets 12and 14 against the membrane-electrode assembly 2 by the seal protrusion12 c.

Thus, the second through fifth embodiments of the present disclosuredescribed below are designed to prevent positional offset between thefirst gasket 12 and the second gasket 14 when they sandwich themembrane-electrode assembly 2. FIG. 8 is a plan view which illustrates agas diffusion layer-integrated gasket for a fuel cell pertaining to asecond embodiment.

That is, in the gas diffusion layer-integrated gasket 1 of the secondembodiment, the differences from the first embodiment describedpreviously are that fitting protrusions 123 are formed on the firstgasket 12, and a plurality of fitting holes 143 are formed on the secondgasket 14. The fitting protrusions 123 and fitting holes 143 areprovided at positions having line symmetry with each other, with thecenter axis of the hinge part 15 as the axis of symmetry. The otherportions can be configured basically in the same way as in the firstembodiment.

The fitting protrusions 123 in the first gasket 12 rise in a shape of arectangular solid, and they are formed at positions close to the twomutually parallel sides of the first gas diffusion layer 11perpendicular to the long direction of the hinge part 15. The fittingholes 143 in the second gasket 15 have an oblong shape which correspondsto the shape of a fitting protrusion 123 projected onto a flat surface,and they are formed at positions close to the two mutually parallelsides of the second gas diffusion layer 13 perpendicular to the longdirection of the hinge part 15.

Furthermore, the fitting protrusions 123 protrude from the surfaceopposite the main rib 12 b—that is, the surface which faces the secondgasket 14 when folded via the hinge part 15. As shown in FIG. 8, theyare positioned outside the seal region (first reaction gas channel F1)surrounded by the main rib 12 b (seal protrusion 12 c), and inparticular, they are positioned between the seal region for the firstgas diffusion layer 11 by the main rib 12 b and the seal region for themanifold holes 121 and 122. Therefore, the fitting holes 143, which arepositioned symmetrically to this, are positioned outside the seal region(second reaction gas channel F2) surrounded by the main rib 14 b, and inparticular, they are positioned between the seal region for the secondgas diffusion layer 13 by the main rib 14 b and the seal region for themanifold holes 141 and 142.

FIG. 9 is a perspective view which illustrates the process ofsandwiching the membrane-electrode assembly by the gas diffusionlayer-integrated gasket for a fuel cell of the second embodiment, FIG.10 is a perspective view which illustrates the state where themembrane-electrode assembly has been sandwiched by the gas diffusionlayer-integrated gasket for a fuel cell of the second embodiment, andFIG. 11 is a cross-sectional view which illustrates the state of fittingbetween the fitting protrusion and fitting hole. That is, in the gasdiffusion layer-integrated gasket 1 pertaining to the second embodimentof the present disclosure configured as described above, as shown inFIG. 9, the first gas diffusion layer 11 and first gasket 12 and thesecond gas diffusion layer 13 and second gasket 14 are folded togethervia the hinge part 15 such that the main ribs oppose each other withrespect to the direction of thickness, while sandwiching themembrane-electrode assembly 2 from both sides in the direction ofthickness. In this state, the manifold holes 121 and 122 of the firstgasket 12 and the manifold holes 141 and 142 of the second gasket 14overlap each other, as shown in FIG. 10.

In this case, the fitting protrusions 123 formed on the first gasket 12fit together with the fitting holes 143 formed on the second gasket 14.Since the fitting protrusions 123 and the fitting holes 143 are formedat positions which are symmetrical to each other with the hinge part 15as the axis of symmetry, the first gasket 12 and the second gasket 15are positioned with high precision due to the fact that the fittingprotrusions 123 and the fitting holes 143 fit together, as shown in FIG.11, and therefore, no offset occurs between the main rib 12 b and sealprotrusion 12 c and the main rib 14 b of the second gasket 14.Therefore, in the stacked state of a fuel cell stack, good contactsurface pressure against the first and second separators 3 and 4 (referto FIG. 1) is obtained due to the compression counterforce of the mainribs 12 b and 14 b, and the compression counterforce of the main ribs 12b and 14 b effectively acts to increase the contact surface pressure ofthe first and second gaskets 12 and 14 against the membrane-electrodeassembly 2 by the seal protrusion 12 c, and as a result, excellentsealing ability is obtained.

For this reason, the stacking operation of the first gas diffusion layer11, first gasket 12, membrane-electrode assembly 2, second gas diffusionlayer 13 and second gasket 14 can be performed without paying attentionto the seal line—that is, without paying attention to whether or not themain rib 12 b, seal protrusion 12 c and main rib 14 b overlap.Therefore, assembly of the fuel-cell cells 10 (refer to FIG. 1) issimple, and operability is improved.

Moreover, before the membrane-electrode assembly 2 is sandwiched betweenthe first gas diffusion layer 11 and first gasket 12 and the seconddiffusion layer 13 and second gasket 14, the fitting protrusions 123have the function of guiding the set position of the membrane-electrodeassembly 2 on top of the first gas diffusion layer 11 and first gasket12, and as a result, fuel cell assembly precision can be even furtherimproved.

Also, because the fitting holes 143 are positioned on the outside of theseal region surrounded by the main rib 14 b in the second gasket 14,fuel gas and oxidant gas supplied to the anode side and cathode side ofthe membrane-electrode assembly 2 via the first gas diffusion layer 11or second gas diffusion layer 13 do not leak out through gaps betweenthe fitting holes 143 and fitting protrusions 123, and they do not getmixed together.

In the third embodiment of the present disclosure shown in FIG. 12,similar to the second embodiment, fitting protrusions 123 on a firstgasket 12 and fitting holes 143 on a second gasket 14 are provided neara hinge part 15.

Furthermore, if non-penetrating fitting indentations 144 are formedinstead of fitting holes 143 on the second gasket 14 such that thesefitting indentations 144 and the fitting protrusions 123 fit togetherwith each other as in the fourth embodiment of the present disclosureshown in FIG. 13, there is no need to be concerned about leakage fromthese fitting parts, and as a result, there is an increased degree offreedom in determining their shape and position.

Next, FIG. 14 is a perspective view which illustrates a gas diffusionlayer-integrated gasket for a fuel cell pertaining to a fifth embodimentof the present disclosure. In this embodiment, the differences from thethird embodiment described above are that fitting protrusions 123 areformed near the four corners of the first gasket 12, and fitting holes143 are formed near the four corners of the second gasket 14 such thatthey are symmetrical to the fitting protrusions 123 with the center axisof the hinge part 15 as the axis of symmetry, and also, the fittingprotrusions 123 have a round pillar shape, and the shape of the openingof the fitting holes 143 is round. Otherwise, it can be configuredbasically in the same way as in the second embodiment.

Therefore, the gas diffusion layer-integrated gasket 1 according to thisembodiment also exhibits the same effect as the second embodiment.

In this case as well, non-penetrating fitting indentations 144 as shownin FIG. 13 may be formed instead of fitting holes 143.

The foregoing description of the embodiments has been provided forpurposes of illustration and description. It is not intended to beexhaustive or to limit the disclosure. Individual elements or featuresof a particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the disclosure, and all such modificationsare intended to be included within the scope of the disclosure.

1. A fuel cell gas diffusion layer integrated gasket comprising: a firstgas diffusion layer; a first gasket which is integrally formed in theperipheral edge of the first gas diffusion layer; a second gas diffusionlayer; a second gasket which is integrally formed in the peripheral edgeof the second gas diffusion layer; and a hinge portion which connectsthe first gasket and the second gasket to each other, wherein the firstgas diffusion layer and the second gas diffusion layer sandwich afilm-electrode complex body having catalyst electrode layers formed onboth surfaces of an electrolyte film from both sides, and wherein aclose contact surface of one of the first gasket and the second gasketis provided with a seal protrusion.
 2. The fuel cell gas diffusion layerintegrated gasket as claimed in claim 1, wherein a fitting protrusion isformed in the first gasket, and a fitting hole or a fitting recessfittable to the fitting protrusion is formed in the second gasket so asto be located at a position symmetrical to the fitting protrusion aboutthe hinge portion as a symmetric axis.